The invention relates to a pitch pocket or pan for sealing mechanical penetrations in a waterproof membrane covering a roof substrate.
In a typical low slope, single-ply membrane roof, provision must be made for sealing penetrations of the roof by vent pipes, support straps, conduits, guy anchors and similar elements. Generally, a pitch pocket or pan which surrounds the penetrating element is used. A sealant is poured into the pan around the penetrating element. Various types of pitch pockets or pans have been proposed. Examples may be found in U.S. Pat. No. 3,838,544 entitled Adjustable Pitch Pocket Structure, which issued on Oct. 1, 1974, to Hindall; U.S. Pat. No. 4,928,443 entitled Pourable Sealer Pocket, which issued on May 29, 1990, to Goodman et al.; U.S. Pat. No. 4,934,117 entitled Pitch Pocket and Method of Forming Same, which issued on Jun. 19, 1990, to Barksdale; and U.S. Pat. No. 4,937,991 entitled Flashing Unit for Sealing Roof Penetrations, which issued on Jul. 3, 1990, to Orth.
In one approach, a prefabricated angle iron flange, at least two inches deep, is fabricated away from the job site. The flange is bonded to the roofing membrane with a solvent-based contact cement, thus forming a metal dam around the roof penetration. Sheet rubber flashing is applied to the outer surfaces of the flange with contact cement to prevent rusting and corrosion. The perimeter of the applied rubber flashing is then sealed with a bead of solvent-based rubber caulking to keep it from being underridden by water. A two-part urethane rubber pourable sealant is mixed and poured into the cavity until it is level with the top of the metal flange. The liquid rubber cures to form a solid rubber seal around the roof penetration.
The installation of available pitch pans is time consuming, complicated and expensive. The process generally takes about 45 minutes per unit and is labor intensive. The complexity of the procedure under field conditions has caused errors in workmanship and improper installations, leading to failure of the seal formed by the pitch pan. Because of the time and expense associated with traditional pitch pans, many contractors have compensated by filling the pan cavity with sand, mortar or urethane foam and covering the top surface with caulk to give the appearance of a solid rubber seal. These practices have lead to frequent leaks and failures that make traditional pitch pans unreliable. Therefore, a need exists for a pitch pocket and installation method which simplifies field application, which reduces the cost of materials and which provides for a more reliable waterproof seal between a roof membrane and penetration therein than heretofore achieved.